Field of the Invention
The invention relates to a sensing apparatus for detecting a user touch.
Description of the Related Art
To increase data security, many electronic products provide fingerprint recognition in the recent years. A most typical fingerprint recognition device includes a sensing region having an area of approximately 1 cm2 for a user to press a fingertip thereon. Below the sensing region are multiple sensing elements in a matrix arrangement. To adapt to gaps between two friction ridges, at least 100*100 (i.e., approximately 10000) sensing elements need to be provided in order to provide a sufficient sensing resolution. If self-capacitive sensing elements are adopted, sensing circuits in the same number as the sensing elements are usually provided in the fingerprint recognition device to respectively drive these sensing elements and receive signals generated by these sensing elements. As the friction ridges and the gaps between the friction ridges pose different levels of influence on the sensing elements, a backend controller is able to determine a fingerprint pattern according to values of signals outputted from the sensing circuits. The above sensing circuit is generally implemented by an integrated circuit. Generally known to one person skilled in the art, the cost of an integrated circuit is directly proportional to the area of a chip. One drawback of such typical fingerprint recognition device is that, in order to coordinate with the size of the sensing region and to accomplish a sufficient sensing resolution, the number of sensing circuits involved is massive, hence resulting in a huge load on hardware costs.
For reducing hardware costs, one kind of conventional fingerprint recognition utilizes a sensing region having a smaller area to reduce the numbers of sensing elements and sensing circuits. A user is required to slide a fingertip on the sensing region to allow the sensing region to gradually scan different parts of the fingerprint. Although such fingerprint recognition device is cheaper, it offers lower ease of use. Further, the incapability of recognition or misjudgment of fingerprint patterns may occasionally occur if the user slides the fingertip at inappropriate speed.
In a typical fingerprint recognition device, each sensing element and the corresponding sensing circuit are connected by an independent connecting line, and so the number of connecting lines between the sensing region and backend circuits is inevitably enormous. As such, if the sensing elements and the backend circuits are packaged in different hardware circuits, these two circuits are forced with huge numbers of external pins due to the enormous number of connecting lines in between, again leading to increased hardware costs. Thus, the sensing region and backend circuits are currently designed to be packaged in the same hardware circuit. However, such unavoidable packaging method limits the flexibility of hardware configuration and fabrication process selection to a certain extent.